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With an emerging need for gasoline particulate filters (GPFs) to lower particle emissions from gasoline direct injection (GDI) engines, studies are being conducted to optimize GPF designs in order to balance filtration efficiency, backpressure penalty, filter size, cost and other factors. Metal fiber filters could offer additional designs to the GPF portfolio, which is currently dominated by ceramic wall-flow filters. However, knowledge on their performance as GPFs is still limited. In this study, modeling on backpressure and filtration efficiency of fibrous media was carried out to determine the basic design criteria (filtration area, filter thickness and size) for different target efficiencies and backpressures at given gas flow conditions. Filter media with different fiber sizes (8 - 17 μm) and porosities (80% - 95%) were evaluated using modeling to determine the influence of fiber size and porosity.

The need for gasoline particulate filter (GPF) technology is expected to grow with increasingly tight particle emissions standards being implemented in US, EU, China and elsewhere. Derived from the successful experience with diesel particulate filters (DPF), GPFs adopted the characteristic alternately plugged honeycomb structure that provides a large area of porous cordierite wall for filtering particles with minimal additional backpressure. However, unlike DPFs, continuous soot regeneration in GPFs makes it difficult to grow and sustain the soot cake on the filter wall that gives DPFs their high filtration efficiency. Therefore, filtration performance of low mileage GPFs relies heavily on the porous structure of filter media, which depends on both the substrate and the applied washcoat. In this work, a blank, two fresh washcoated filters and two washcoated filters with 3000 km mileage accumulation were characterized to compare their filtration performance.

The increasing use of gasoline direct injection (GDI) engines coupled with the implementation of new particulate matter (PM) and particle number (PN) emissions regulations requires new emissions control strategies. Gasoline particulate filters (GPFs) present one approach to reduce particle emissions. Although primarily composed of combustible material which may be removed through oxidation, particle also contains incombustible components or ash. Over the service life of the filter the accumulation of ash causes an increase in exhaust backpressure, and limits the useful life of the GPF. This study utilized an accelerated aging system to generate elevated ash levels by injecting lubricant oil with the gasoline fuel into a burner system. GPFs were aged to a series of levels representing filter life up to 150,000 miles (240,000 km). The impact of ash on the filter pressure drop and on its sensitivity to soot accumulation was investigated at specific ash levels.